1. Field of the Invention
The invention relates in general to an apparatus for detection for use in a touch-sensitive pad and a method therefor, and more particularly to an apparatus for detection for use in a wireless touch-sensitive pad operative with power saving and a method therefor.
2. Description of the Related Art
Computer systems nowadays employ a lot of peripheral devices. For a computer system employing many peripheral devices, the required cables and lines for connecting the peripheral devices to the computer system are inconvenient to be arranged. In order to reduce number of the cables and lines for connection and make the peripheral devices capable of being moved easily and used in a distance from the computer system, many kinds of peripheral devices are redesigned to be wireless, resulting in wireless peripheral devices, such as a wireless keyboard and a wireless mouse, available to the market. If touch-sensitive pads, or simply called touch pads, are substituted for conventional mice, the touch pads and keyboards can be further integrated into one device, resulting in a compact peripheral device with reduced number of cables and lines, and convenient mobile capability.
Power dissipation is an important problem to be resolved. The power dissipated by a wireless device should be as less as possible because the wireless device cannot gain power externally but requires batteries internally equipped with it. Although touch pads are generally of capacitor-type, their dissipation power in a sleep mode is still substantially large, about 800 μ. Another type of touch pad is resistive touch pad. A resistive touch pad is illustrated in FIG. 1. A touch pad 100 includes an X layer 102 and a Y layer 104. The X layer 102 and the Y layer 104 are planar resistors and the X layer 102 has no contact with the Y layer 104 under natural states. On the X layer 102, the value of resistance varies with the X-axis, but not with the Y-axis . On the Y layer 104, the value of resistance varies with the Y-axis , but not with the X-axis. When a user touches the touch pad 100, the X layer 102 will be in contact with the Y layer 104 at a touching point. For example, in FIG. 1, a point P1 on the Y layer 104 and a point P2 on the X layer 102 make contact with each other at a touching point as the user touches the touch pad 100. The coordinates of the touching point varies as the user is touching the touch pad 100 with movement on the touch pad 100. The touch pad 100 employs a detection device for detecting the coordinates of the touching point. In order to reduce the dissipation power of the touch pad, the reduction in the dissipation power of the detection device to a minimum level becomes one of the important tasks of the industry to be taken efforts in.